AVR Provides a Better Alternative Than Screen Scraping, ASNA Says
November 1, 2005 Alex Woodie
There are a plethora of options available to OS/400 shops looking to modernize or migrate their monolithic RPG applications using a service oriented architecture. One of the quickest and easiest ways is to implement a screen scraper that outputs the 5250 datastream as a Web service. ASNA says it has a better way with its ASNA Visual RPG (AVR) for .NET offering. Last week the company unveiled AVR for .NET version 7.2, which adds support for more RPG functions, as well as expanded printing capabilities.
In a new white paper titled, “Screen Scraping: A Wolf in Sheep’s Clothing” posted on ASNA’s Web site, the company touts its AVR for .NET software as a more attractive and secure path to modernization than screen scraping. While screen scraping is quick, relatively painless, and easily adaptable to the latest interface technologies (in this case, XML and Web services), it has fundamental problems that can’t be ignored, the company claims.
The biggest drawback to screen scraping, ASNA says, is that it creates a new metadata model to the database that developers must maintain if data integrity is to be maintained. (Actually, ASNA says that assuming that IBM will continue to support and maintain the OS/400 server is the biggest risk to screen scraping, but the majority of OS/400 shops have already made their gamble, and will probably continue to leave their chips in the game.)
ASNA explains that this metadata model must be maintained because screen scraping technologies basically ignore the underlying database, and often combine information from different screens into a new interface. So when changes are made to the production application–which is to say that changes are made to the database–this metadata model also must be updated, or the company risks jumbling the data.
By contrast, AVR for .NET directly accesses the DB2/400 database, via the DataGate Component Suite (DCS), and has other benefits, the company says. AVR for .NET, a language that is syntactically similar to RPG, plugs into Microsoft‘s popular Visual Studio development environment, and compiles code into a Microsoft Intermediate Language (MSIL)-compliant .NET assembly that can be executed on Windows. You don’t see IBM writing Windows compilers for RPG, but this is what ASNA has been providing for users and ISVs for more than a decade.
AVR enables RPG developers to write new business logic that runs on Windows servers and accesses DB2/400 or Microsoft SQL Server databases via DCS, which is included with AVR and is also sold separately. AVR works very well with existing RPG applications, ASNA says, and users also benefit from being able to use any of the Visual Studio languages to extend their core OS/400 applications.
ASNA also positions AVR as a tool for whole-hog migrations from the OS/400-RPG-DB2/400 stack to the Windows Server-Visual Studio .NET-SQL Server stack. Wholesale conversions are easier now that ASNA has put together a suite of migration tools, called Monarch, that includes DDS and CL converters, a code analysis tool, and a project management application. ASNA first released Monarch about a year ago, and updated the toolset in August.
AVR for .NET 7.2
Whichever path users take–modernization and extension, or migration–AVR is ASNA’s core offering. Last month the San Antonio, Texas, company unveiled AVR for .NET version 7.2, the first new release of the product in more than a year, and the second release since the .NET-compatible tool was introduced in the summer of 2003.
AVR for .NET 7.2 delivers better compatibility with existing RPG applications, including those written in RPG/400, ILE RPG, and AVR for COM, an older version of AVR that works with Microsoft’s precursor to .NET, Component Object Model. For example, AVR 7.2 delivers support for more than 21 additional ILE RPG Built-In Functions (BIFs) and adds the capability to declare subfields from input fields. What’s more, keyed file I/O commands (such as CHAIN and SETLL, among others) have been enhanced to use an inline list of keys in lieu of a conventional key list, ASNA says.
This release also includes a new Subfile control, which will help customers migrate from AVR for COM to AVR for .NET, ASNA says. This Windows client control serves as an alternative to the .NET framework’s Windows Data Grid control, and emulates many of the properties, methods, and events of the AVR for COM Subfile control, the company says.
Perhaps the biggest enhancement with AVR 7.2 is a new report printing engine and print file design tool. The new Visual Studio-based Print File Designer generates reports from Windows and Web applications, outputs reports in XML, and can be used with third-party reporting products, such as Crystal Reports, ASNA says.
Anne Ferguson, president and co-founder of ASNA, says the new report printing engine brings superb Windows printing to AVR for .NET applications. “AVR 7.2 is a major step forward, particularly for those interested in continuing to extend or migrate code,” she says. “We’re very excited about AVR 7.2 and its synchronicity with ASNA Monarch 2.0.”